/Engine/Source/Runtime/Engine/Public/TextureResource.h
FVirtualTexture2DResourcemay have an AllocatedVT, which represents a page table allocation for the virtual texture. VTs used by materials generally don't need their own allocation, since the material has its own page table allocation for each VT stack. VTs used as lightmaps need their own allocation. Also VTs open in texture editor will have a temporary allocation.GetAllocatedVT()will return the current allocation if one exists.AcquireAllocatedVT()will make a new allocation if needed, and return it.ReleaseAllocatedVT()will free any current allocation.
[IAllocatedVirtualTexture](API\Runtime\RenderCore\IAllocatedVirtualTexture) * GetAllocatedVT() const